import tkinter as tk
root = tk.Tk()
texto = tk.StringVar(value='Texto inicial')
texto.set(value='TextoVariable')

tk.Label(root, text='Hola Mundo').pack(anchor='nw')

label = tk.Label(root)
label.pack(anchor='center')

tk.Label(root, text='Hola Saturno').pack(anchor='se')

label.config(bg='green', fg='blue', font=('Verdana',24))
label.config(textvariable=texto)

root.mainloop()